The logic of charcoal

Why does charcoal burn? Isn't it already burned? Or is it only mostly burned? What gives?

-- B.C., O'side

Charcoal is carefully cooked wood. Mankind figured out this one many centuries ago. The head-producing part of fuel is carbon. Increase the relative amount of carbon in your cooker, and you can roast that haunch of mountain goat or yak fillet and can get out of the kitchen in half the time. Wood is about 50 percent carbon (coal is 90). You can up your wood-based carbon by reducing the wood's hydrogen and oxygen content. It's still done pretty much the way it was centuries ago. Logs are baked slowly at very high temperatures in a low-oxygen oven. This drives off most of the liquids and leaves the carbon.

The funky, ubiquitous charcoal briquette, with less snob appeal than true charcoal, is made from roasted wood scrap, binders, and other chemicals compressed into a little cake. It's a spinoff of Henry Ford's auto assembly line. To squeeze a buck from the waste scraps of steering wheel and dashboard wood, they cooked it, smashed it into a lump, and gave it a fancy name. At one time, you could buy charcoal briquettes only at Ford dealerships.